Well you cannot possibly grow a forum with the malware warning poping up. Anyone new would be scared away and never view it as a future option. Most people are not savy enough to trust what anyone says as far as how safe it is, so existing users are not frequenting like they used to. So now we have no growth for two years and a declining user base... guess what that means.
I still go there once a day but it is obvious there are only a small number of active users.
If they ever get this fixed they will need to work hard to get it back to its pre hacked state. Many people have moved on to more localized google groups and facebook groups like this one